FILE - In this Sept. 29, 2013, file photo, Denver Broncos quarterback Peyton Manning (18) drops back to pass for a touchdown against the Philadelphia Eagles in the third quarter of an NFL football game in Denver. Manning's next touchdown throw will be his 500th, and if the trend holds true, it will be caught by a tight end, not a wide receiver. Denver plays at home against Arizona on Sunday, Oct. 5, 2014. (AP Photo/Jack Dempsey, File)

"There's always things we can improve on," Manning said after the Denver Broncos scored more points than they ever had in their 54-year history in a 52-20 demolition of the Philadelphia Eagles on Sunday.

Manning's hair was still wet but his brain already had moved on to the next game, against the Dallas Cowboys (2-2) next weekend.

"We have a tough road game next week, another unfamiliar opponent," Manning said, his unemotional, even-keeled approach matching the cold-blooded efficiency he had just displayed in producing another batch of records on a picturesque Autumn afternoon in the Rocky Mountains.

Manning threw four more TD passes and the Broncos (4-0) added two special teams scores, pulling away from the Eagles (1-3), who were close at halftime.

Manning's 16 TD passes are the most for any quarterback in the first month of an NFL season, besting the previous mark of 14 set by Don Meredith in 1966 and tied by Kurt Warner in 1999. He also joined Milt Plum in 1960 as the only quarterbacks to throw that many touchdown passes without an interception.

After last season's playoff pratfall, Manning realizes it will all mean nothing if the Broncos don't parlay this fantastic start into an equally excellent finish in four months.

That's why setting the franchise record of 15 straight regular-season wins was no cause for celebration.

"The recaps don't mean a whole lot," Manning said. "It was a good win because it was this game and we'll learn from it and we have a tough test next week playing a team that we're unfamiliar with, that is a good football team, that is tough to play at home.

"I think we'll enjoy this win and we'll learn from it. But you have to move on to the next week pretty quickly."

Five reasons why the Eagles (1-3) couldn't knock the Broncos from the unbeaten ranks:

BRONCOS BASH: After Chris Polk's 4-yard touchdown run cut Philly's deficit to 14-12, first-year Eagles coach Chip Kelly, who was famous for never taking his foot off the gas at Oregon, went for the PAT instead of the 2-point conversion. The Broncos scored the next 31 points.

"Might have to give old Thunder an I.V. after this one," Manning said of the white Arabian gelding who trots around the Sports Authority Field following touchdowns.

If there's any I.V. bags left, that is.

With two TD passes each to Demaryius Thomas and Wes Welker, Manning completed all but a half dozen of his 34 throws for 327 yards, and he didn't even step on the field in the fourth quarter.

SPECIAL TEAMS: The Broncos' special teams got into the act again, scoring on Trindon Holliday's 105-yard kickoff return and Steven Johnson's 17-yard return of his own blocked punt.

"I was just unblocked," Johnson said. "I was going to rush the center and he got out of the way, and I said, 'OK, I'll go block the punt."

Those special teams contributions helped Denver surpass the franchise scoring record of 50 points set against San Diego on Oct. 6, 1963.

LINEBACKER LAMENTS: Only the 1966 Dallas Cowboys, with 183 points, scored more than the Broncos' 179 in their first four games.

Just think, if linebacker Danny Trevathan hadn't fumbled his would-be pick-6 in the opener in premature celebration, the Broncos would be the most proficient point-producer in NFL history.

"We all learned from that," said Johnson, who nevertheless held out the football as he neared the goal line on his punt return TD before tucking it in just as he saw punter Donnie Jones swooping in from his right.

SHORTNESS OF BREATH: All week long, Kelly downplayed the altitude, saying it wouldn't be a factor.

The thin air certainly wasn't just in Eagles running back LeSean McCoy's mind. He needed a few breathers on the sideline to get some supplemental oxygen into his lungs.

"I just couldn't breathe," said McCoy, who carried the ball 16 times for 73 yards.

THIRD DOWNS: Teams always talk about getting off the field on third down, but the Eagles couldn't even put the Broncos in third-down situations to begin with.

Manning drove Denver on a trio of touchdown drives in the third quarter covering 80, 80 and 65 yards, and not once did the Broncos face a third down in any of them.

Denver collected 35 first downs overall and only five of them were on third-down conversions.

"I think it is disconcerting," Kelly said. "But you're also playing against an offense that four teams have tried to stop them and they haven't yet."